Semiconductor device with different fin pitches

ABSTRACT

A method for forming a semiconductor device includes forming a first fin and a second fin on a substrate, the first fin arranged in parallel with the second fin, the first fin arranged a first distance from the second fin, the first fin and the second fin extending from a first source/drain region through a channel region and into a second source/drain region on the substrate. The method further includes forming a third fin on the substrate, the third fin arranged in parallel with the first fin and between the first fin and the second fin, the third fin arranged a second distance from the first fin, the second distance is less than the first distance, the third fin having two distal ends arranged in the first source/drain region. A gate stack is formed over the first fin and the second fin.

BACKGROUND

The present invention generally relates to complimentary metal-oxidesemiconductors (CMOS) and metal-oxide-semiconductor field-effecttransistors (MOSFET), and more specifically, to finFET devicefabrication.

The MOSFET is a transistor used for switching electronic signals. TheMOSFET has a source, a drain and a metal oxide gate electrode. The metalgate is electrically insulated from the main semiconductor n-channel orp-channel by a thin layer of insulating material, for example, silicondioxide or high dielectric constant (high-k) dielectrics, which makesthe input resistance of the MOSFET relatively high. The gate voltagecontrols whether the path from drain to source is an open circuit(“off”) or a resistive path (“on”).

N-type field effect transistors (nFET) and p-type field effecttransistors (pFET) are two types of complementary MOSFETs. The nFET hasn-doped source and drain junctions and uses electrons as the currentcarriers. The pFET has p-doped source and drain junctions and uses holesas the current carriers.

The finFET is a type of MOSFET. The finFET is a multiple-gate MOSFETdevice that mitigates the effects of short channels and reducesdrain-induced barrier lowering. The “fin” refers to a semiconductormaterial patterned on a substrate that often has three exposed surfacesthat form the narrow channel between source and drain regions. A thindielectric layer arranged over the fin separates the fin channel fromthe gate. Because the fin provides a three dimensional surface for thechannel region, a larger channel length may be achieved in a givenregion of the substrate as opposed to a planar FET device.

Gate spacers form an insulating film along the gate sidewalls. Gatespacers may also initially be formed along sacrificial gate sidewalls inreplacement gate technology. The gate spacers are used to definesource/drain regions in active areas of a semiconductor substratelocated adjacent to the gate.

Device scaling in the semiconductor industry reduces costs, decreasespower consumption and provides faster devices with increased functionsper unit area. Improvements in optical lithography have played a majorrole in device scaling. However, optical lithography has limitations forminimum dimensions and pitch, which are determined by the wavelength ofthe irradiation.

SUMMARY

According to an embodiment of the present invention, a method forforming a semiconductor device includes forming a first fin and a secondfin on a substrate, the first fin arranged in parallel with the secondfin, the first fin arranged a first distance from the second fin, thefirst fin and the second fin extending from a first source/drain regionthrough a channel region and into a second source/drain region on thesubstrate. The method further includes forming a third fin on thesubstrate, the third fin arranged in parallel with the first fin andbetween the first fin and the second fin, the third fin arranged asecond distance from the first fin, the second distance is less than thefirst distance, the third fin having two distal ends arranged in thefirst source/drain region. A gate stack is formed over the first fin andthe second fin.

According to another embodiment of the present invention a semiconductordevice comprises a first semiconductor fin arranged on a substrate, thefirst semiconductor fin having a first distal end, a second distal end,and a medial region arranged between the first distal end and the seconddistal end, the first distal end of the first semiconductor fin arrangedin a first source/drain region and the second distal end of the secondsemiconductor fin arranged in a second source/drain region. The devicefurther comprises a second semiconductor fin arranged on the substrate,the second semiconductor fin having a first distal end, a second distalend, and a medial region arranged between the first distal end and thesecond distal end, the second distal end of the second semiconductor finarranged in the first source/drain region and the second distal end ofthe second semiconductor fin arranged in the second source/drain region.A third semiconductor fin is arranged on the substrate, the thirdsemiconductor fin having a first distal end, a second distal end, and amedial region arranged between the first distal end and the seconddistal end, the first distal end and the second distal end of the thirdsemiconductor fin arranged in the first source/drain region. The firstsemiconductor fin, the second semiconductor fin, and the thirdsemiconductor fin are arranged substantially in parallel with eachother, the third semiconductor fin is arranged between the firstsemiconductor fin and the second semiconductor fin, the firstsemiconductor fin is arranged a first distance from the secondsemiconductor fin and the third semiconductor fin is arranged a seconddistance from the first semiconductor fin, the first distance greaterthan the second distance. A gate stack is arranged over a channel regionof the first semiconductor fin and the second semiconductor fin betweenthe first source/drain region and the second source/drain region.

According to yet another embodiment of the present invention, a methodfor forming a semiconductor device comprises forming a mandrel on asubstrate, forming sacrificial sidewall spacers along sidewalls of themandrel, and removing the mandrel. The method further comprises removingportions of the substrate to form an arrangement of fins on thesubstrate. The arrangement of fins includes a first fin arrangedsubstantially in parallel with a second fin in a source/drain region,the first fin arranged a first distance from the second fin and a thirdfin arranged substantially in parallel with a fourth fin in a channelregion, the third fin arranged a second distance from the fourth fin,the second distance is greater than the first distance. The sacrificialsidewall spacers are removed and a gate stack is formed over the channelregion.

According to yet another embodiment of the present invention, asemiconductor device comprises a first semiconductor fin arranged inparallel with a second semiconductor fin in a first source/drain regionon a substrate. The first semiconductor fin is arranged a first distancefrom the second semiconductor fin. The device further comprises a thirdsemiconductor fin arranged in parallel with a fourth semiconductor finin a channel region on the substrate, the third semiconductor fin isarranged a second distance from the fourth semiconductor fin, the seconddistance greater than the first distance, the first semiconductor fincontacting the third semiconductor fin and the second semiconductor fincontacting the fourth semiconductor fin. A gate stack is arranged overthe channel region of the third semiconductor fin and the fourthsemiconductor fin.

According to yet another embodiment of the present invention, a methodfor forming a semiconductor device comprises forming a mandrel on asubstrate, forming sacrificial sidewall spacers along sidewalls of themandrel, and removing the mandrel. Portions of the substrate are removedto form an arrangement of fins on the substrate. The arrangement of finsincludes a first fin arranged substantially in parallel with a secondfin in a source/drain region, the first fin is arranged a first distancefrom the second fin and a third fin is arranged substantially inparallel with a fourth fin in a channel region. The third fin isarranged a second distance from the fourth fin, the first distance isgreater than the second distance. The sacrificial sidewall spacers areremoved, and a gate stack is formed over the channel region.

According to yet another embodiment of the present invention, asemiconductor device comprises a first semiconductor fin arranged inparallel with a second semiconductor fin in a first source/drain regionon a substrate, the first semiconductor fin arranged a first distancefrom the second semiconductor fin. The device further comprises a thirdsemiconductor fin arranged in parallel with a fourth semiconductor finin a channel region on the substrate, the third semiconductor fin isarranged a second distance from the fourth semiconductor fin, the firstdistance is greater than the second distance. The first semiconductorfin contacts the third semiconductor fin and the second semiconductorfin contacts the fourth semiconductor fin. A gate stack is arranged overthe channel region of the third semiconductor fin and the fourthsemiconductor fin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-19 illustrate an exemplary method for fabricating a finFETdevice using a sidewall image transfer process with fins having agreater fin pitch in the channel region and a smaller fin pitch in thesource/drain regions.

FIG. 1 illustrates a side view of a semiconductor substrate, a hardmaskarranged on the substrate, and a sacrificial layer arranged on thehardmask.

FIG. 2 illustrates a top view following the patterning of a mask on thesemiconductor layer.

FIG. 3 illustrates a top view following an anisotropic etching process.

FIG. 4 illustrates a cut-away view along the line A-A (of FIG. 3)showing a portion of the mandrel arranged on the hardmask.

FIG. 5 illustrates a cut-away view along the line B-B (of FIG. 3)showing another portion of the mandrel arranged on the hardmask.

FIG. 6 illustrates a top view following the formation of sacrificialsidewall spacers along sidewalls of the mandrel.

FIG. 7 illustrates a cut-away view along the line A-A (of FIG. 6) of aportion of the sacrificial sidewall spacers.

FIG. 8 illustrates a cut-away view along the line B-B (of FIG. 6) ofanother portion of the sacrificial sidewall spacers.

FIG. 9 illustrates a top view following the removal of the mandrel (ofFIG. 6).

FIG. 10 illustrates a top view following a selective etching processthat removes exposed portions of the hardmask and the substrate to formfins.

FIG. 11 illustrates a cut-away view along the line A-A (of FIG. 10) offins that are arranged on the substrate.

FIG. 12 illustrates a cut-away view along the line B-B (of FIG. 10) ofanother portion of the fins.

FIG. 13 illustrates a top view following the removal of the sacrificialsidewall spacers (of FIG. 10), which exposes the hardmask.

FIG. 14 illustrates a top view following the formation of a sacrificialgate over the fins (of FIG. 13) and spacers adjacent to sidewalls of thesacrificial gate.

FIG. 15 illustrates a top view following the formation of source/drainregions over the fins (of FIG. 14).

FIG. 16 illustrates a cut-away view along the line A-A (of FIG. 15) ofthe fins the substrate and the source/drain region formed over the finsand the substrate.

FIG. 17 illustrates a top view following the formation of an inter-leveldielectric layer and the removal of the sacrificial gate (of FIG. 15) toform a cavity that exposes the channel regions of the fins.

FIG. 18 illustrates a top view of the resultant structure following theformation of a replacement metal gate stack.

FIG. 19 illustrates a cut-away view along the line B-B (of FIG. 18) ofthe gate stack.

FIGS. 20-25 illustrate an exemplary method for fabricating a finFETdevice using a sidewall image transfer process with fins having agreater fin pitch in the channel region and a smaller fin pitch in thesource/drain regions.

FIG. 20 illustrates a top view of following the formation of sacrificialsidewall spacers along sidewalls of the mandrel.

FIG. 21 illustrates a top view following an anisotropic etching processthat removes exposed portions of the substrate and forms fins.

FIG. 22 illustrates a cut-away view along the line A-A (of FIG. 21) ofthe fins.

FIG. 23 illustrates a cut-away view along the line B-B (of FIG. 21) ofthe fins.

FIG. 24 illustrates a cut-away view along the line C-C (of FIG. 21) ofthe fins and a merged fin portion.

FIG. 25 illustrates a top view following the formation of a gate stackand spacers along sidewalls of the gate stack.

FIG. 26 illustrates a top view that is partially transparent of fins.

FIG. 27 illustrates a top view that is partially transparent of fins.

FIGS. 28-32 illustrate an exemplary direct patterning method forfabricating a finFET device having a greater fin pitch in the channelregion and a smaller fin pitch in the source/drain regions.

FIG. 28 illustrates a top view of an arrangement of fins on a substrate.

FIG. 29 illustrates a top view following the formation of a sacrificialgate stack, spacers, and source/drain regions over the fins (of FIG.28).

FIG. 30 illustrates a top view following the formation of an inter-leveldielectric layer over the source/drain regions (of FIG. 29) and areplacement gate stack over channel regions of the fins.

FIG. 31 illustrates a cut-away view along the line A-A (of FIG. 30) ofthe fins and the source/drain region.

FIG. 32 illustrates a cut-away view along the line B-B (of FIG. 30) ofthe fins and the gate stack arranged over the fins.

FIG. 33 illustrates a top view of an alternate exemplary arrangement offins.

DETAILED DESCRIPTION

FinFETs typically include a fin that has a three dimensional profilearranged on a substrate. Previous finFETs often included a fin that hasa channel region, a gate stack arranged over the channel region andsource/drain regions on opposing sides of the channel region. The sizeand shape of the fin was substantially uniform through the source/drainregions and the channel region.

In finFET devices with multiple fins arranged in parallel on asubstrate, the spacing between the fins (i.e., fin pitch) wassubstantially uniform between the portions of the fins in thesource/drain region and the channel regions. In other words, for a pairof identical fins arranged adjacent to each other and in parallel on asubstrate, the distance between the fins is the same in the channelregion and the source/drain region.

For high voltage finFETs or some other types of finFETs, a relativelythick gate dielectric and work function metal are desirable to meetperformance parameters of such devices. However, as the fin pitch isreduced in order to reduce the scale of the devices on the substrate,the space available between the fins in the channel region becomessmaller. If the desired thickness of the gate dielectric and workfunction metal is relatively thick compared to the distance between thefins in the channel region, there simply may not be enough space betweenthe fins in the channel region to form a proper multi-gate device.

The illustrated exemplary methods and embodiments describe a finFETdevice that has fins in the channel region that are sufficiently pitchedto allow the deposition of gate dielectric and work function metals at adesired thickness while maintaining the desired performancecharacteristics of a multi-gate device. The embodiments described hereinfurther provide for fins in the source/drain regions that are spaced ata different pitch than the channel region to allow a uniform formationof epitaxially grown source/drain regions.

FIGS. 1-19 illustrate an exemplary method for fabricating a finFETdevice using a sidewall image transfer process with fins having agreater fin pitch in the channel region and a smaller fin pitch in thesource/drain regions.

FIG. 1 illustrates a side view of a semiconductor substrate 102, ahardmask 104 arranged on the substrate 102, and a sacrificial layer 106arranged on the hardmask 104.

Non-limiting examples of suitable materials for the substrate 102include Si (silicon), strained Si, SiC (silicon carbide), Ge(germanium), SiGe (silicon germanium), SiGeC (silicon-germanium-carbon),Si alloys, Ge alloys, III-V materials (e.g., GaAs (gallium arsenide),InAs (indium arsenide), InP (indium phosphide), or aluminum arsenide(AlAs)), II-VI materials (e.g., CdSe (cadmium selenide), CdS (cadmiumsulfide), CdTe (cadmium telluride), ZnO (zinc oxide), ZnSe (zincselenide), ZnS (zinc sulfide), or ZnTe (zinc telluride)), or anycombination thereof. Other non-limiting examples of semiconductormaterials include III-V materials, for example, indium phosphide (InP),gallium arsenide (GaAs), aluminum arsenide (AlAs), or any combinationthereof. The III-V materials may include at least one “III element,”such as aluminum (Al), boron (B), gallium (Ga), indium (In), and atleast one “V element,” such as nitrogen (N), phosphorous (P), arsenic(As), antimony (Sb).

The hardmask 104 may include, for example, silicon oxide, siliconnitride (SiN), SiOCN, SiBCN or any suitable combination of those. Thehardmask 104 may be deposited using a deposition process, including, butnot limited to, PVD, CVD, PECVD, or any combination thereof. Thesacrificial layer 106 may include, any suitable material such as, forexample, amorphous carbon or amorphous silicon.

FIG. 2 illustrates a top view following the patterning of a mask 202 onthe sacrificial layer 106. Suitable resist masks include photoresists,electron-beam resists, ion-beam resists, X-ray resists and etch resists.The resist may a polymeric spin on material or a polymeric material.

FIG. 3 illustrates a top view following an anisotropic etching processsuch as, for example, reactive ion etching that removes exposed portionsof the sacrificial layer 106 (of FIG. 2) to form a mandrel 302 arrangedon the hardmask 104.

FIG. 4 illustrates a cut-away view along the line A-A (of FIG. 3)showing a portion of the mandrel 302 arranged on the hardmask 104. FIG.5 illustrates a cut-away view along the line B-B (of FIG. 3) showinganother portion of the mandrel 302 arranged on the hardmask 104.

FIG. 6 illustrates a top view following the formation of sacrificialsidewall spacers 602 along sidewalls of the mandrel 302. The sacrificialsidewall spacers 602 may be formed by, for example, depositing a layerof spacer material (not shown) over the exposed portions of the hardmask104 and the mandrel 302. Non-limiting examples of suitable materials forthe layer of spacer material include dielectric oxides (e.g., siliconoxide), dielectric nitrides (e.g., silicon nitride), dielectricoxynitrides, or any combination thereof. The layer of spacer material isdeposited by a suitable deposition process, for example, chemical vapordeposition (CVD) or physical vapor deposition (PVD).

Following the deposition of the layer of spacer material, a suitableanisotropic etching process such as, for example, a reactive ion etchingprocess is performed to remove portions of the layer of spacer materialand form sacrificial sidewall spacers 602.

FIG. 7 illustrates a cut-away view along the line A-A (of FIG. 6) of aportion of the sacrificial sidewall spacers 602. FIG. 8 illustrates acut-away view along the line B-B (of FIG. 6) of another portion of thesacrificial sidewall spacers 602.

FIG. 9 illustrates a top view following the removal of the mandrel 302(of FIG. 6) using a suitable selective etching process that selectivelyremoves the mandrel 302 without substantially removing or damaging thesacrificial sidewall spacers 602 or the hardmask 104.

FIG. 10 illustrates a top view following a selective etching processthat removes exposed portions of the hardmask 104 and the substrate 102to form fins.

FIG. 11 illustrates a cut-away view along the line A-A (of FIG. 10) offins 1102 that are arranged on the substrate 102. The fins 1102 arespaced (pitched) a distance x and will be used in subsequent fabricationprocesses to form the source/drain regions of the finFET device. FIG. 12illustrates a cut-away view along the line B-B (of FIG. 10) of anotherportion of the fins 1202 that are pitched a distance y and will be usedin subsequent fabrication processes to form the channel region of thedevice. In the illustrated exemplary embodiment shown in FIGS. 11-12 thedistance x is less than the distance y.

FIG. 13 illustrates a top view following the removal of the sacrificialsidewall spacers 602 (of FIG. 10), which exposes the hardmask 104.

FIG. 14 illustrates a top view following the formation of a sacrificialgate 1404 over the fins 1202 (of FIG. 13) and spacers 1402 adjacent tosidewalls of the sacrificial gate 1404.

The sacrificial gates 1404 in the exemplary embodiment are formed bydepositing a layer (not shown) of sacrificial gate material such as, forexample, amorphous silicon (aSi), or polycrystalline silicon(polysilicon) material or another suitable sacrificial gate material.The sacrificial gate 1404 may further comprises a sacrificial gatedielectric material such as silicon oxide between the nanowires and aSior polysilicon material.

The layer sacrificial gate material may be deposited by a depositionprocess, including, but not limited to, physical vapor deposition (PVD),chemical vapor deposition (CVD), atomic layer deposition (ALD, plasmaenhanced chemical vapor deposition (PECVD), inductively coupled plasmachemical vapor deposition (ICP CVD), or any combination thereof.

Following the deposition of the layer of sacrificial gate material, ahard mask layer (not shown) such as, for example, silicon oxide, siliconnitride (SiN), SiOCN, SiBCN or any suitable combination of thosematerials, is deposited on the layer of sacrificial gate material toform a PC hard mask or sacrificial gate cap (not shown). The hardmasklayer may be deposited using a deposition process, including, but notlimited to, PVD, CVD, PECVD, or any combination thereof.

Following the deposition of the layer sacrificial gate material and thehardmask layer, a lithographic patterning and etching process such as,for example, reactive ion etching or a wet etching process is performedto remove exposed portions of the hardmask layer and the layer ofsacrificial gate material form the sacrificial gates 1404 and thesacrificial gate caps.

In FIG. 14, spacers 1402 are formed adjacent to the sacrificial gates1404. The spacers 1402 in the illustrated embodiment are formed bydepositing a layer of spacer material (not shown) over the exposedportions of the substrate 102, the fins 1202, and the sacrificial gates1404. Non-limiting examples of suitable materials for the layer ofspacer material include dielectric oxides (e.g., silicon oxide),dielectric nitrides (e.g., silicon nitride), dielectric oxynitrides, orany combination thereof. The layer of spacer material is deposited by asuitable deposition process, for example, chemical vapor deposition(CVD) or physical vapor deposition (PVD).

Following the deposition of the layer of spacer material, a suitableanisotropic etching process such as, for example, a reactive ion etchingprocess is performed to remove portions of the layer of spacer materialand form the spacers 1402.

FIG. 15 illustrates a top view following the formation of source/drainregions 1502 over the fins 1102 (of FIG. 14). The source/drain regions1502 are formed by an epitaxial growth process that deposits acrystalline overlayer of semiconductor material onto the exposedcrystalline seed material of the exposed fin 1202 to form thesource/drain regions 1502.

Epitaxial materials may be grown from gaseous or liquid precursors.Epitaxial materials may be grown using vapor-phase epitaxy (VPE),molecular-beam epitaxy (MBE), liquid-phase epitaxy (LPE), or othersuitable process. Epitaxial silicon, silicon germanium, and/or carbondoped silicon (Si:C) silicon can be doped during deposition (in-situdoped) by adding dopants, n-type dopants (e.g., phosphorus or arsenic)or p-type dopants (e.g., boron or gallium), depending on the type oftransistor. The dopant concentration in the source/drain can range from1×10¹⁹ cm⁻³ to 2×10²¹ cm⁻³, or between 2×10²⁰ cm⁻³ and 1×10²¹ cm⁻³.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” mean the growth of a semiconductor material (crystallinematerial) on a deposition surface of another semiconductor material(crystalline material), in which the semiconductor material being grown(crystalline overlayer) has substantially the same crystallinecharacteristics as the semiconductor material of the deposition surface(seed material). In an epitaxial deposition process, the chemicalreactants provided by the source gases are controlled and the systemparameters are set so that the depositing atoms arrive at the depositionsurface of the semiconductor substrate with sufficient energy to moveabout on the surface such that the depositing atoms orient themselves tothe crystal arrangement of the atoms of the deposition surface.Therefore, an epitaxially grown semiconductor material has substantiallythe same crystalline characteristics as the deposition surface on whichthe epitaxially grown material is formed. For example, an epitaxiallygrown semiconductor material deposited on a {100} orientated crystallinesurface will take on a {100} orientation. In some embodiments, epitaxialgrowth and/or deposition processes are selective to forming onsemiconductor surface, and generally do not deposit material on exposedsurfaces, such as silicon dioxide or silicon nitride surfaces.

In some embodiments, the gas source for the deposition of epitaxialsemiconductor material include a silicon containing gas source, agermanium containing gas source, or a combination thereof. For example,an epitaxial Si layer may be deposited from a silicon gas source that isselected from the group consisting of silane, disilane, trisilane,tetrasilane, hexachlorodisilane, tetrachlorosilane, dichlorosilane,trichlorosilane, methylsilane, dimethylsilane, ethylsilane,methyldisilane, dimethyldisilane, hexamethyldisilane and combinationsthereof. An epitaxial germanium layer can be deposited from a germaniumgas source that is selected from the group consisting of germane,digermane, halogermane, dichlorogermane, trichlorogermane,tetrachlorogermane and combinations thereof. While an epitaxial silicongermanium alloy layer can be formed utilizing a combination of such gassources. Carrier gases like hydrogen, nitrogen, helium and argon may beused.

FIG. 16 illustrates a cut-away view along the line A-A (of FIG. 15) ofthe fins 1102 the substrate 102 and the source/drain region 1502 formedover the fins 1102 and the substrate 102.

FIG. 17 illustrates a top view following the formation of an inter-leveldielectric layer 1702 and the removal of the sacrificial gate 1404 (ofFIG. 15) to form a cavity 1701 that exposes the channel regions of thefins 1202. The inter-level dielectric layer 1702 is formed from, forexample, a low-k dielectric material (with k<4.0), including but notlimited to, silicon oxide, spin-on-glass, a flowable oxide, a highdensity plasma oxide, borophosphosilicate glass (BPSG), or anycombination thereof. The inter-level dielectric layer 1702 is depositedby a deposition process, including, but not limited to CVD, PVD, plasmaenhanced CVD, atomic layer deposition (ALD), evaporation, chemicalsolution deposition, or like processes. Following the deposition of theinter-level dielectric layer 1702, a planarization process such as, forexample, chemical mechanical polishing is performed.

The sacrificial gates 1404 may be removed by performing a dry etchprocess, for example, RIE, followed by a wet etch process. The wet etchprocess is selective to (will not substantially etch) the spacers 1402and the inter-level dielectric material. The chemical etch process mayinclude, but is not limited to, hot ammonia or tetramethylammoniumhydroxide (TMAH).

FIG. 18 illustrates a top view of the resultant structure following theformation of a replacement metal gate stack (gate stack) 1801. FIG. 19illustrates a cut-away view along the line B-B (of FIG. 18) of the gatestack 1801. The gate stack 1801 includes high-k metal gates formed, forexample, by filling the cavity 1701 (of FIG. 17) with one or more gatedielectric 1902 materials, one or more workfunction metals 1904, one ormore metal gate conductor 1906 materials, and a gate cap 1802. The gatedielectric 1902 material(s) can be a dielectric material having adielectric constant greater than 3.9, 7.0, or 10.0. Non-limitingexamples of suitable materials for the dielectric 1902 materials includeoxides, nitrides, oxynitrides, silicates (e.g., metal silicates),aluminates, titanates, nitrides, or any combination thereof. Examples ofhigh-k materials (with a dielectric constant greater than 7.0) include,but are not limited to, metal oxides such as hafnium oxide, hafniumsilicon oxide, hafnium silicon oxynitride, lanthanum oxide, lanthanumaluminum oxide, zirconium oxide, zirconium silicon oxide, zirconiumsilicon oxynitride, tantalum oxide, titanium oxide, barium strontiumtitanium oxide, barium titanium oxide, strontium titanium oxide, yttriumoxide, aluminum oxide, lead scandium tantalum oxide, and lead zincniobate. The high-k material may further include dopants such as, forexample, lanthanum and aluminum.

The gate dielectric 1902 materials may be formed by suitable depositionprocesses, for example, chemical vapor deposition (CVD), plasma-enhancedchemical vapor deposition (PECVD), atomic layer deposition (ALD),evaporation, physical vapor deposition (PVD), chemical solutiondeposition, or other like processes. The thickness of the dielectricmaterial may vary depending on the deposition process as well as thecomposition and number of high-k dielectric materials used. Thedielectric material layer may have a thickness in a range from about 0.5to about 20 nm.

The work function metal(s) 1904 may be disposed over the gate dielectric1902 material. The type of work function metal(s) 1904 depends on thetype of transistor and may differ between the nFET and pFET devices.Non-limiting examples of suitable work function metals 1904 includep-type work function metal materials and n-type work function metalmaterials. P-type work function materials include compositions such asruthenium, palladium, platinum, cobalt, nickel, and conductive metaloxides, or any combination thereof. N-type metal materials includecompositions such as hafnium, zirconium, titanium, tantalum, aluminum,metal carbides (e.g., hafnium carbide, zirconium carbide, titaniumcarbide, and aluminum carbide), aluminides, or any combination thereof.The work function metal(s) may be deposited by a suitable depositionprocess, for example, CVD, PECVD, PVD, plating, thermal or e-beamevaporation, and sputtering.

The gate conductor 1906 material(s) is deposited over the gatedielectric 1902 materials and work function metal(s) 1904 to form thegate stack 1801. Non-limiting examples of suitable conductive metalsinclude aluminum (Al), platinum (Pt), gold (Au), tungsten (W), titanium(Ti), or any combination thereof. The gate conductor 1906 material(s)may be deposited by a suitable deposition process, for example, CVD,PECVD, PVD, plating, thermal or e-beam evaporation, and sputtering.

Following the deposition of the gate dielectric 1902 materials, the workfunction metal(s) 1904, and the gate conductor 1906 material(s),planarization process, for example, chemical mechanical planarization(CMP), is performed to remove the overburden of the deposited gatematerials and form the gate stack 1801.

FIGS. 20-25 illustrate an exemplary method for fabricating a finFETdevice using a sidewall image transfer process with fins having agreater fin pitch in the channel region and a smaller fin pitch in thesource/drain regions.

FIG. 20 illustrates a top view of following the formation of sacrificialsidewall spacers 2002 along sidewalls of the mandrel 302. The resultantstructure is formed using a similar process as described above in FIGS.1-6 however; the sacrificial sidewall spacers 2002 are wider than thesacrificial sidewall spacers 602 (of FIG. 6). The sacrificial sidewallspacers 2002 may be formed by depositing a relatively thicker layer ofspacer material followed by an etch back process that forms thesacrificial sidewall spacers 2002.

FIG. 21 illustrates a top view following an anisotropic etching processthat removes exposed portions of the substrate 102 and forms fins 2102and 2104. Following the formation of the fins 2102 and 2104, thesacrificial sidewall spacer 2002 is removed using, for example aselective etching process. FIG. 22 illustrates a cut-away view along theline A-A (of FIG. 21) of the fins 2102. FIG. 23 illustrates a cut-awayview along the line B-B (of FIG. 21) of the fins 2104. FIG. 24illustrates a cut-away view along the line C-C (of FIG. 21) of the fins2102 and a merged fin portion 2402. The merged fin portion 2402 ispartially defined by the intersection of the fins 2102 and 2104. Thefins 2102 are spaced (pitched) a distance x′ and will be used insubsequent fabrication processes to form the source/drain regions of thefinFET device. The fins 2104 that are pitched a distance y′ and will beused in subsequent fabrication processes to form the channel region ofthe device. In the illustrated exemplary embodiment shown in FIGS. 22-23the distance x′ is less than the distance y′.

FIG. 25 illustrates a top view following the formation of a gate stack1801 and spacers 1402 along sidewalls of the gate stack 1801 and aninter-level dielectric layer 1702 that are formed using a processsimilar to the gate stack formation process described above.

FIG. 26 illustrates a top view that is partially transparent of fins1102 and 1202. FIG. 26 is similar to FIG. 14 described above however;the spacers 1402 and gate stack 1801 are slightly offset in alignmentwith the fins 1102 and 1202 such that portions of the fins 1102 in theregion 2601 are arranged below the gate stack 1801. The offset inalignment of the gate stack 1801 results in portions of the fins 1202 inthe region 2603 are arranged below the spacer 1402.

FIG. 27 illustrates a top view that is partially transparent of fins2101 and 2104. FIG. 27 is similar to FIG. 21 described above however;the spacers 1402 and gate stack 1801 are slightly offset in alignmentwith the fins 2101 and 2104 such that portions of the fins 2101 in theregion 2701 are arranged below the gate stack 1801. The offset inalignment of the gate stack 1801 results in portions of the fins 2101 inthe region 2703 are arranged below the spacer 1402.

FIGS. 28-32 illustrate an exemplary direct patterning method forfabricating a finFET device having a greater fin pitch in the channelregion and a smaller fin pitch in the source/drain regions.

FIG. 28 illustrates a top view of an arrangement of fins 2802 and fins2804 on a substrate 102. The fins 2802 and fins 2804 in the illustratedembodiment have been formed by a lithographic patterning and etchingprocess such as, for example, reactive ion etching that removessemiconductor material to form the fins 2802 and 2804.

FIG. 29 illustrates a top view following the formation of a sacrificialgate stack 1404, spacers 1402, and source/drain regions 2902 over thefins 2802 (of FIG. 28) using a similar process as described above.

FIG. 30 illustrates a top view following the formation of an inter-leveldielectric layer 1702 over the source/drain regions 2902 (of FIG. 29)and a replacement gate stack 1801 over channel regions of the fins 2804.

FIG. 31 illustrates a cut-away view along the line A-A (of FIG. 30) ofthe fins 2802 and the source/drain region 2902. FIG. 32 illustrates acut-away view along the line B-B (of FIG. 30) of the fins 2804 and thegate stack 1802 arranged over the fins 2804. The fins 2802 are spaced(pitched) a distance x″ and form a portion of the source/drain regionsof the finFET device. The fins 2804 that are pitched a distance y″ andwill be used in subsequent fabrication processes to form the channelregion of the device. In the illustrated exemplary embodiment shown inFIGS. 28-32 the distance x″ is less than the distance y″.

FIG. 33 illustrates a top view of an alternate exemplary arrangement offins 3300. The fins 3300 are formed using a similar process as describedabove in FIGS. 1-13 however, the pattern of the fins is such that thefins 3302 that are arranged in the source/drain region have a largerpitch than the fins 3304 that are arranged in the channel region.Following the formation of the arrangement of the 3300, a similarprocess as described above in FIGS. 14-19 may be performed to form afinFET device with a gate stack over the fins 3304 and source/drainregion over the fins 3302.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method for forming a semiconductor device, themethod comprising: forming a first fin and a second fin on a substrate,the first fin arranged substantially in parallel with the second fin,the first fin arranged a first distance from the second fin, the firstfin and the second fin extending from a first source/drain regionthrough a channel region and into a second source/drain region on thesubstrate; forming a third fin on the substrate, the third fin arrangedsubstantially in parallel with the first fin and between the first finand the second fin, the third fin arranged a second distance from thefirst fin, the second distance is less than the first distance, thethird fin having two distal ends arranged in the first source/drainregion; forming a gate stack over the first fin and the second fin inthe channel region; and growing a crystalline semiconductor material onexposed portions of the first fin, the second fin, and the third fin, inthe first source/drain region.
 2. The method of claim 1, wherein thefirst fin, the second fin, and the third fin include a semiconductormaterial.
 3. The method of claim 1, wherein the first fin, the secondfin, and the third fin, are formed by an anisotropic etching process. 4.The method of claim 1, wherein forming the first fin, the second fin,and the third fin includes: forming a hardmask on the substrate; andperforming a lithographic patterning and etching process to removeexposed portions of the hardmask and substrate materials to form thefirst fin, the second fin, and the third fin.
 5. The method of claim 1,wherein a pitch of the first fin and the second fin is greater than apitch of the first fin and the third fin.
 6. The method of claim 1,wherein the crystalline semiconductor material is in-situ doped.
 7. Themethod of claim 1, wherein the crystalline semiconductor material isdoped using an ion implantation process.
 8. The method of claim 1,further comprising depositing an insulator layer over the crystallinesemiconductor material.
 9. The method of claim 1, further comprisingforming a spacer adjacent to the gate stack.
 10. A semiconductor devicecomprising: a first semiconductor fin arranged on a substrate, the firstsemiconductor fin having a first distal end, a second distal end, and amedial region arranged between the first distal end and the seconddistal end, the first distal end of the first semiconductor fin arrangedin a first source/drain region and the second distal end of the secondsemiconductor fin arranged in a second source/drain region; a secondsemiconductor fin arranged on the substrate, the second semiconductorfin having a first distal end, a second distal end, and a medial regionarranged between the first distal end and the second distal end, thesecond distal end of the second semiconductor fin arranged in the firstsource/drain region and the second distal end of the secondsemiconductor fin arranged in the second source/drain region; a thirdsemiconductor fin arranged on the substrate, the third semiconductor finhaving a first distal end, a second distal end, and a medial regionarranged between the first distal end and the second distal end, thefirst distal end and the second distal end of the third semiconductorfin arranged in the first source/drain region; wherein the firstsemiconductor fin, the second semiconductor fin, and the thirdsemiconductor fin are arranged substantially in parallel with eachother, the third semiconductor fin arranged between the firstsemiconductor fin and the second semiconductor fin, the firstsemiconductor fin arranged a first distance from the secondsemiconductor fin and the third semiconductor fin arranged a seconddistance from the first semiconductor fin, the first distance greaterthan the second distance; and a gate stack arranged over a channelregion of the first semiconductor fin and the second semiconductor finbetween the first source/drain region and the second source/drainregion.
 11. The device of claim 10, further comprising a spacer arrangedalong sidewalls of the gate stack.
 12. The device of claim 10, furthercomprising a crystalline semiconductor material contacting the firstdistal end of the first semiconductor fin, the first distal end of thesecond semiconductor fin, and the first distal end and the second distalend of the third semiconductor fin.
 13. The device of claim 10, furthercomprising a spacer arranged over the second distal end of the thirdsemiconductor fin.
 14. The device of claim 10, wherein the gate stackincludes a metal gate material.
 15. The device of claim 10, wherein thefirst semiconductor fin includes silicon.
 16. The device of claim 10,wherein the first semiconductor fin includes silicon germanium.
 17. Thedevice of claim 11, wherein the spacer includes a nitride material or anoxide material.
 18. The device of claim 12, wherein the crystallinesemiconductor material includes a dopant.
 19. A semiconductor device,comprising: a first semiconductor fin structure in a first source/drainregion on a substrate, the first semiconductor fin structure beingdefined by sides separated by a first distance; a second semiconductorfin structure in a channel region on the substrate, the secondsemiconductor fin structure being defined by sides separated by a seconddistance, the second distance being greater than the first distance, thefirst semiconductor fin structure contacting the second semiconductorfin structure; a third semiconductor fin structure in a secondsource/drain region on the substrate, the third semiconductor finstructure being defined by sides separated by a third distance, thesecond distance being greater than the third distance, the thirdsemiconductor fin structure contacting the second semiconductor finstructure; and a gate stack arranged over the channel region of thesecond semiconductor fin structure.